Hurricane Harvey was given Category 3 status on Friday afternoon, Aug. 25.
Ahead of Hurricane Harvey, Texas Gov. Greg Abbott requested a major disaster declaration, which will trigger additional help from the federal government. "This is going to be a very major disaster," Abbott said Friday, warning of record-breaking flooding across south Texas.
The outer bands of Hurricane Harvey have begun swiping the Texas coast as 35 inches of rain and "catastrophic" storm-surge flooding is predicted after landfall late Friday or early Saturday, the National Hurricane Center said.
The combination of heavy rain, "life-threatening" storm surges, flooding and strong winds could leave wide swaths of South Texas "uninhabitable for weeks or months," the National Weather Service in Houston said. Such daunting language hasn't been seen by CNN's experts since Hurricane Katrina, which left more than 1,800 people dead in 2005.
Harvey, still a Category 2 hurricane, is on track to strengthen to Category 3, with winds of at least 111 mph by the time it makes landfall around Corpus Christi, forecasters said.
A hurricane warning is in effect for about 1.5 million people, with another 16 million under a tropical storm warning, the weather service said.
"Texas is about to have a very significant disaster," said Brock Long, director of the Federal Emergency Management Agency.
Residents were urged to evacuate. A mass exodus from the coast caused extensive traffic jams along the state's highways, while other people boarded up windows and stocked up on food and water ahead of the storm, the effects of which are expected to last for days.
After landfall, the storm will stall and dump rain on South Texas and parts of Louisiana into the middle of next week, forecasters predicted.
"All indications from the hurricane center are that this is going to be the first major hurricane the nation has dealt with since 2005," Long said.
-- Harvey strengthened early Friday, becoming a Category 2 hurricane with winds up to 110 mph, according to the National Weather Service.
-- "The water is going to be the issue," Corpus Christi Mayor Joe McComb said. "We've never had anything like this."
-- Isolated tornadoes are possible Friday across portions of the middle and upper Texas coast, the service said.
-- Texas Gov. Greg Abbott has requested the activation of 700 National Guard members.
-- "We are prepared; we are not panicking," Galveston Mayor James Yarbrough said.
-- The Ports of Corpus Christi and Galveston are closed. Three Galveston-based cruise ships in the Gulf of Mexico diverted to safer water.
FEMA prepared for 'significant disaster'
Those who stay should "elevate and get into a structure that can withstand potentially Category 3 winds from a hurricane," said Long, the FEMA director.
"The bottom line message is, right now, if people have not heeded the warning, again, their window to do so is closing," Long said. "If they refuse to heed the warning, that's on them."
Long said he is "very worried" about storm surge, or "wind-driven water," slamming coastal areas, saying it has the "highest potential to kill the most amount of people and cause the most amount of damage."
"Over the next five days, we're going to see copious amounts of rainfall, up to 25 inches, possibly, in some areas, with isolated higher amounts," he said. "This is going to be a slow-developing major disaster event for the state of Texas."
FEMA has pre-positioned incident management teams, as well as life-saving and life-sustaining commodities, and search-and-rescue teams in Texas, Long said.
President Donald Trump tweeted that he has spoken with the governors of Texas and Louisiana, saying he is "closely monitoring Hurricane Harvey developments and here to assist as needed."
"I think we'll be looking at the potential request for presidential disaster declarations coming up from Gov. Abbott," Long said. "The President has the ability, has the authority to sign off on those to mobilize our support to the state governments."
Officials also worried that Harvey's abundant rain will drench Texas and the region for several days.
"We could see this storm park for almost five days in some places, and we hear 3 feet of rain," said Bill Read, the former director of the National Hurricane Center. "That's just going to be a huge problem for these areas."
Harvey is also causing concern in New Orleans, where heavy rain could usher in as much as 20 inches of rain through early next week and overwhelm the city's already-compromised drainage system.
In a statement Friday to CNN, US Customs and Border Protection and Immigration and Customs Enforcement said that "routine noncriminal immigration enforcement operations will not be conducted at evacuation sites, or assistance centers such as shelters or food banks."
'I'm trying to be strong'
The threat of Harvey became evident Thursday when several coastal Texas counties issued evacuation orders, leading to hordes of residents sitting bumper to bumper miles.
Rose Yepez told CNN it took her twice as long as usual to drive 140 miles from Corpus Christi to San Antonio, en route to Texas Hill Country.
Private vehicles -- along with city buses packed with adults and children carrying backpacks -- jammed roads for hours.
"I'm shaking inside, but for them, I'm trying to be strong," a Corpus Christi woman who was waiting with her two daughters to board a bus out of town told CNN affiliate KRIS.
Workers at 39 offshore petroleum production platforms and an oil rig in the Gulf of Mexico also evacuated Thursday, the Bureau of Safety and Environmental Enforcement said.
Houston Mayor Sylvester Turner said anyone not leaving should plan to stay off the roads once the storm starts.
"People need to know, this is not a one-, two-day event and done," Turner said. "Even though it may seem like it will get better, this is a four- or five-day event, starting tomorrow evening, going through Monday or Tuesday."
Staying put, boarding up
First responders like Brittany Fowler stayed behind and waited for the storm.
"Hopefully it doesn't do any damage, but if it does, we've prepared," Fowler, a firefighter in Corpus Christi, wrote on Instagram.
Fowler's family helped by boarding up windows and doors at her home, and she bought plenty of water, food and a small power generator.
Corey Davis, by contrast, was free to go -- but opted to stay put, even as Harvey's winds started blowing Thursday night. Instead of packing, she and her relatives took turns climbing a tall ladder to secure plywood over windows at their Port O'Connor home.
"I'm scared, so I'm doing everything that I can to protect (this) little place down here," Davis told CNN affiliate KTRK, "and hope and pray for the best."
Despite the warnings, Elsie and David Reichenbacher prepped supplies and plan to stay put in Corpus Christi.
"I've gone through a lot of hurricanes. I've lived here most of my life," Elsie Reichenbacher said. "I'd rather take care of my home and my animals and be safe here. I'm on high ground with my house."
™ & © 2017 Cable News Network, Inc., a Time Warner Company. All rights reserved.